A new principle for fast and inexpensive evaluation of the size, depth and elastic moduli of small lesions in the breast using mechanical sensor is developed. The long term objective of this project is to realize the new principle in a clinical device for mass breast screening and early detection of cancer. Mathematical modeling, together with clinical and biophysical studies have shown that the propose approach is capable of detecting smaller lesions and at greater depths than conventional manual palpation. The device comprises a probe equipped with an array of pressure sensors, a computer, a computer interface for the probe and software for dynamic pressure pattern analysis, enabling one to reconstruct specific geometrical and mechanical features of the breast tissues. This device uses no hazardous radiation and is entirely safe. It can serve as a mass screening technique complementary to X-ray mammography. Specific aims of the project are to design an experimental setup and confirm the theoretically estimate resolution and sensitivity of the propose method, develop tissue phantoms mimicking mechanical properties of normal and diseased breast and, using these phantoms, test the propose approach on mechanical models of breast with various types of cancer.